[Fleet] Remove duplicative retries from client-side requests to APIs that depend on EPR (#190722)

## Summary

Relates to https://github.com/elastic/kibana/issues/136617

For APIs that depend on Fleet connecting to Elastic Package Registry,
Fleet already retries the connections to EPR on the server side. This
results in a situation where, when EPR is unreachable, the requests is
retried several times on the server side, and then the request is
retried again on the client-side by react-query. This results in very
long running API requests.

Since the server-side retries generally cover any kind of flakiness
here, disabling the retry logic on the front-end seems sensible. ~I've
also reduced the number of retries on the server side from 5 to 3 to
help fail faster here.~ I walked back the retry change after some test
failures, and I don't think it makes a big enough impact to justify
changing.

## To test

Set `xpack.fleet.registryUrl: 127.0.0.1:8080` with nothing running

## Before

The requests spin for a very long time.


https://github.com/user-attachments/assets/e4fd77ee-b36c-4965-9f71-e5b3e195f75e

## After

The requests stop spinning after a few seconds as the retries won't
loop.


https://github.com/user-attachments/assets/82adc595-1bc4-4269-8501-2eb83525ad15

cc @shahzad31

x-pack/plugins/fleet/public/applications/integrations/sections/epm/components/package_list_grid/grid.tsx

@@ -7,12 +7,18 @@
 
 import React, { useCallback, useRef, useEffect, forwardRef } from 'react';
 import { css } from '@emotion/react';
-import { EuiFlexGrid, EuiFlexItem, EuiSpacer, EuiText, EuiAutoSizer } from '@elastic/eui';
+import {
+  EuiFlexGrid,
+  EuiFlexItem,
+  EuiSpacer,
+  EuiText,
+  EuiAutoSizer,
+  EuiSkeletonRectangle,
+} from '@elastic/eui';
 import { VariableSizeList as List } from 'react-window';
 import { FormattedMessage } from '@kbn/i18n-react';
 import { WindowScroller } from 'react-virtualized';
 
-import { Loading } from '../../../../components';
 import type { IntegrationCardItem } from '../../screens/home';
 
 import { PackageCard } from '../package_card';
@@ -66,7 +72,17 @@ export const GridColumn = ({
     }
   }, []);
 
-  if (isLoading) return <Loading />;
+  if (isLoading) {
+    return (
+      <EuiFlexGrid gutterSize="l" columns={3}>
+        {Array.from({ length: 12 }).map((_, index) => (
+          <EuiFlexItem key={index} grow={3}>
+            <EuiSkeletonRectangle height="160px" width="100%" />
+          </EuiFlexItem>
+        ))}
+      </EuiFlexGrid>
+    );
+  }
 
   if (!list.length) {
     return (

x-pack/plugins/fleet/public/applications/integrations/sections/epm/screens/home/category_facets.tsx

@@ -5,7 +5,7 @@
  * 2.0.
  */
 
-import { EuiFacetButton, EuiFacetGroup } from '@elastic/eui';
+import { EuiFacetButton, EuiFacetGroup, EuiSpacer } from '@elastic/eui';
 import type { IntegrationCategory } from '@kbn/custom-integrations-plugin/common';
 import React from 'react';
 
@@ -78,7 +78,11 @@ export function CategoryFacets({
   const controls = (
     <EuiFacetGroup>
       {isLoading ? (
-        <Loading />
+        <>
+          <EuiSpacer size="m" />
+          <Loading size="l" />
+          <EuiSpacer size="m" />
+        </>
       ) : (
         categories.map((category) => {
           return (

x-pack/plugins/fleet/public/hooks/use_request/epm.ts

@@ -54,13 +54,16 @@ export function useGetReplacementCustomIntegrationsQuery() {
 }
 
 export function useGetCategoriesQuery(query: GetCategoriesRequest['query'] = {}) {
-  return useQuery<GetCategoriesResponse, RequestError>(['categories', query], () =>
-    sendRequestForRq<GetCategoriesResponse>({
-      path: epmRouteService.getCategoriesPath(),
-      method: 'get',
-      query,
-      version: API_VERSIONS.public.v1,
-    })
+  return useQuery<GetCategoriesResponse, RequestError>(
+    ['categories', query],
+    () =>
+      sendRequestForRq<GetCategoriesResponse>({
+        path: epmRouteService.getCategoriesPath(),
+        method: 'get',
+        query,
+        version: API_VERSIONS.public.v1,
+      }),
+    { retry: (_, error) => !isRegistryConnectionError(error), refetchOnWindowFocus: false }
   );
 }
 
@@ -96,6 +99,8 @@ export const useGetPackagesQuery = (
         query,
       }),
     enabled: options?.enabled,
+    retry: (_, error) => !isRegistryConnectionError(error),
+    refetchOnWindowFocus: false,
   });
 };
 
@@ -151,7 +156,12 @@ export const useGetPackageInfoByKeyQuery = (
           ...(ignoreUnverifiedQueryParam && { ignoreUnverified: ignoreUnverifiedQueryParam }),
         },
       }),
-    { enabled: queryOptions.enabled, refetchOnMount: queryOptions.refetchOnMount }
+    {
+      enabled: queryOptions.enabled,
+      refetchOnMount: queryOptions.refetchOnMount,
+      retry: (_, error) => !isRegistryConnectionError(error),
+      refetchOnWindowFocus: false,
+    }
   );
 
   const confirm = async () => {
@@ -360,3 +370,7 @@ export function useGetInputsTemplatesQuery(
       })
   );
 }
+
+function isRegistryConnectionError(error: RequestError) {
+  return error.statusCode === 502;
+}