chore: migrate from legacylibrarian to release-please for releasing (googleapis#17474)

Author: codyoss

.github/release-please.yml

@@ -0,0 +1,17 @@
+handleGHRelease: true
+manifest: true
+tagPullRequestNumber: true
+
+branches:
+  - branch: main
+    handleGHRelease: true
+    tagPullRequestNumber: true
+    manifest: true
+    manifestFile: .release-please-bulk-manifest.json
+    manifestConfig: release-please-bulk-config.json
+  - branch: main
+    handleGHRelease: true
+    tagPullRequestNumber: true
+    manifest: true
+    manifestFile: .release-please-individual-manifest.json
+    manifestConfig: release-please-individual-config.json