Allow resolveTransportVersionConflict to run on release branches

Transport version generation must only happen on the main branch. The
resolveTransportVersionConflict task exists to deal with merge conflicts
when syncing a PR with main. However, conflicts can also arise when
cherry-picking a commit for backport. This commit updates the task to
also handle cherry picks to older branches.

Author: rjernst

build-tools-internal/src/integTest/groovy/org/elasticsearch/gradle/internal/transport/AbstractTransportVersionFuncTest.groovy

@@ -167,6 +167,10 @@ class AbstractTransportVersionFuncTest extends AbstractGradleFuncTest {
         execute("git init")
         execute('git config user.email "build-tool@elastic.co"')
         execute('git config user.name "Build tool"')
+        file(".gitignore") << """
+        .gradle/
+        build/
+        """.stripIndent()
         execute("git add .")
         execute('git commit -m "Initial"')
     }

build-tools-internal/src/integTest/groovy/org/elasticsearch/gradle/internal/transport/ResolveTransportVersionConflictFuncTest.groovy

@@ -145,11 +145,6 @@ class ResolveTransportVersionConflictFuncTest extends AbstractTransportVersionFu
 
     def "resolve on release branch accepts upstream"() {
         given:
-        file("myserver/build.gradle") << """
-            tasks.named('resolveTransportVersionConflict') {
-                currentUpperBoundName = '9.1'
-            }
-        """
         // setup main with 2 commits, but we will only cherry pick the second one
         execute("git checkout main")
         referableAndReferencedTransportVersion("upstream_new_tv1", "8124000")
@@ -163,6 +158,15 @@ class ResolveTransportVersionConflictFuncTest extends AbstractTransportVersionFu
         execute("git commit -m update2")
         String toCherryPick = execute("git rev-parse HEAD")
         execute("git checkout test") // test is a faux 9.1 branch
+        file("myserver/build.gradle") << """
+            tasks.named('resolveTransportVersionConflict') {
+                currentUpperBoundName = '9.1'
+            }
+            tasks.named('validateTransportVersionResources') {
+                currentUpperBoundName = '9.1'
+            }
+        """
+        execute("git commit -a -m update-branch")
         execute("git cherry-pick " + toCherryPick, testProjectDir.root, true);
 
         when:

build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/transport/ResolveTransportVersionConflictTask.java

@@ -22,7 +22,7 @@ protected void runGeneration(TransportVersionResourcesService resources, List<Tr
 
         if (onReleaseBranch) {
             if (resources.hasCherryPickConflicts()) {
-                getLogger().lifecycle("Resolving transport version merge conflicts by checking accepting upstream changes...");
+                getLogger().lifecycle("Resolving transport version conflicts by accepting upstream changes...");
                 resources.checkoutOriginalChange();
             } else {
                 getLogger().lifecycle("No transport version merge conflicts detected");