ci: Fix rules used to determine when to upload Conan recipes (#6524)

The refs as previously used pointed to the source branch, not the target branch. However, determining the target branch is different depending on the GitHub event. The pull request logic was incorrect and needed to be fixed, and the logic inside the workflow could be simplified. Both modifications have been made in this commit.

.github/workflows/on-pr.yml

@@ -142,7 +142,7 @@ jobs:
       - should-run
       - build-test
     # Only run when committing to a PR that targets a release branch.
-    if: ${{ github.repository == 'XRPLF/rippled' && needs.should-run.outputs.go == 'true' && startsWith(github.ref, 'refs/heads/release') }}
+    if: ${{ github.repository == 'XRPLF/rippled' && needs.should-run.outputs.go == 'true' && github.event_name == 'pull_request' && startsWith(github.event.pull_request.base.ref, 'release') }}
     uses: ./.github/workflows/reusable-upload-recipe.yml
     secrets:
       remote_username: ${{ secrets.CONAN_REMOTE_USERNAME }}

.github/workflows/reusable-upload-recipe.yml

@@ -69,22 +69,28 @@ jobs:
           conan export . --version=${{ steps.version.outputs.version }}
           conan upload --confirm --check --remote="${REMOTE_NAME}" xrpl/${{ steps.version.outputs.version }}
 
+      # When this workflow is triggered by a push event, it will always be when merging into the
+      # 'develop' branch, see on-trigger.yml.
       - name: Upload Conan recipe (develop)
-        if: ${{ github.ref == 'refs/heads/develop' }}
+        if: ${{ github.event_name == 'push' }}
         env:
           REMOTE_NAME: ${{ inputs.remote_name }}
         run: |
           conan export . --version=develop
           conan upload --confirm --check --remote="${REMOTE_NAME}" xrpl/develop
 
+      # When this workflow is triggered by a pull request event, it will always be when merging into
+      # one of the 'release' branches, see on-pr.yml.
       - name: Upload Conan recipe (rc)
-        if: ${{ startsWith(github.ref, 'refs/heads/release') }}
+        if: ${{ github.event_name == 'pull_request' }}
         env:
           REMOTE_NAME: ${{ inputs.remote_name }}
         run: |
           conan export . --version=rc
           conan upload --confirm --check --remote="${REMOTE_NAME}" xrpl/rc
 
+      # When this workflow is triggered by a tag event, it will always be when tagging a final
+      # release, see on-tag.yml.
       - name: Upload Conan recipe (release)
         if: ${{ github.event_name == 'tag' }}
         env: