Skip input step when triggering JDK matrix jobs (#15733) (#15734)

PR#15729 missed the input step. As a result when the job is triggered
the steps are executed, but the pause icon still shows in the job
requiring manual unblock[^1]

This commit also skips the input step when the job is triggered from
the scheduler pipeline.

[^1] https://buildkite.com/elastic/logstash-linux-jdk-matrix-pipeline/builds/86

(cherry picked from commit a8b64a32e9)

Co-authored-by: Dimitrios Liappis <dimitrios.liappis@gmail.com>

.buildkite/linux_jdk_matrix_pipeline.yml

@@ -6,7 +6,7 @@ env:
 
 steps:
   - input: "Test Parameters"
-    if: build.source != "schedule"
+    if: build.source != "schedule" && build.source != "trigger_job"
     fields:
       - select: "Operating System"
         key: "matrix-os"

.buildkite/windows_jdk_matrix_pipeline.yml

@@ -6,7 +6,7 @@ env:
 
 steps:
   - input: "Test Parameters"
-    if: build.source != "schedule"
+    if: build.source != "schedule" && build.source != "trigger_job"
     fields:
       - select: "Operating System"
         key: "matrix-os"