Rewind failed release 1.15.0

[felixbarny]

The released failed with this message:

14:40:19 [INFO] [ERROR] Failed to execute goal org.apache.maven.plugins:maven-deploy-plugin:2.8.2:deploy (default-deploy) on project apm-agent-parent: Failed to deploy artifacts: Could not transfer artifact co.elastic.apm:apm-agent-parent:pom:1.15.0 from/to sonatype-nexus-staging (https://oss.sonatype.org/service/local/staging/deploy/maven2/): Failed to transfer file: https://oss.sonatype.org/service/local/staging/deploy/maven2/co/elastic/apm/apm-agent-parent/1.15.0/apm-agent-parent-1.15.0.pom. Return code is: 504, ReasonPhrase: Gateway Time-out. -> [Help 1]

Despite the sonatype status being green, Staging Operation Duration indicates some problems:

This PR has been created like this:

git revert --no-commit 79f939f429127bf362d46d21f777bd10f6b513ff
git revert --no-commit fef23b2521800847598a0f916ad8f707d88a3455
git commit -am "Restore version 1.14.0-SNAPSHOT"

[felixbarny]

I have deleted the 1.15.0 tag with these commands:

git push --delete origin v1.15.0
git tag --delete v1.15.0