This commit removes the RequestBuilder generic type from Action. It was
needed to be used by the newRequest method, which in turn was used by
client.prepareExecute. Both of these methods are now removed, along with
the existing users of prepareExecute constructing the appropriate
builder directly.
The errors were caused because release tests would use a copy of
the public key that was formatted differently. The change to the
public key format was introduced in [1].
Release tests Jenkins job has now been updated to use the correct
key format depending on the branch they run on [2]
Closes#30430
[1] https://github.com/elastic/elasticsearch/pull/30251
[2] https://github.com/elastic/infra/pull/4944
