Reusable workflows from a common repository

* Remove `release-files-spec.json` and `spring-project-init.gradle`
since they come from a common repository as well

.github/workflows/ci-snapshot.yml

@@ -8,5 +8,5 @@ on:
 
 jobs:
   build-snapshot:
-    uses: spring-projects/spring-integration-aws/.github/workflows/spring-artifactory-gradle-snapshot.yml@main
+    uses: artembilan/spring-messaging-build-tools/spring-artifactory-gradle-snapshot.yml@main
     secrets: inherit

.github/workflows/pr-build.yml

@@ -7,4 +7,4 @@ on:
 
 jobs:
   build-pull-request:
-    uses: spring-projects/spring-integration-aws/.github/workflows/spring-gradle-pull-request-build.yml@main
+    uses: artembilan/spring-messaging-build-tools/spring-gradle-pull-request-build.yml@main

.github/workflows/release.yml

@@ -7,7 +7,7 @@ run-name: Release current version for branch ${{ github.ref_name }}
 
 jobs:
   release:
-    uses: spring-projects/spring-integration-aws/.github/workflows/spring-artifactory-release.yml@main
+    uses: artembilan/spring-messaging-build-tools/spring-artifactory-release.yml@main
     with:
       buildToolArgs: dist
     secrets: inherit