chore: remove All rights reserved clause from java.header (#1148) (#13)

After discussion with OSPO, it has been decided to remove "All rights reserved" clause from the java.header file to better reflect the [correct license header](https://g3doc.corp.google.com/company/teams/opensource/releasing/preparing.md?cl=head#Apache-header).
Source-Link: googleapis/synthtool@09c59c2
Post-Processor: gcr.io/repo-automation-bots/owlbot-java:latest@sha256:2e88a4a7fe3377cf8de1fa5982134f6ef2768980fa2f94edcc1ba6604ae2e7ca

.github/.OwlBot.lock.yaml

@@ -1,3 +1,3 @@
 docker:
-  digest: sha256:a9b83a276c82987d284b733713fe86a3c8a2cc457933767eeb2688b882e54c6a
-  image: gcr.io/repo-automation-bots/owlbot-java:latest
+  image: gcr.io/repo-automation-bots/owlbot-java:latest
+  digest: sha256:2e88a4a7fe3377cf8de1fa5982134f6ef2768980fa2f94edcc1ba6604ae2e7ca

java.header

@@ -1,5 +1,5 @@
 ^/\*$
-^ \* Copyright \d\d\d\d,? Google (Inc\.|LLC)( All [rR]ights [rR]eserved\.)?$
+^ \* Copyright \d\d\d\d,? Google (Inc\.|LLC)$
 ^ \*$
 ^ \* Licensed under the Apache License, Version 2\.0 \(the "License"\);$
 ^ \* you may not use this file except in compliance with the License\.$