Remove unneeded git rev parse

In case when git checkout method is running inside docker container
which is run under root, dir() and checkout() steps will be run under
jenkins user outside of container and sh step under root user (using docker exec).
After fixes of security https://ubuntu.com/security/CVE-2022-24765 git rev
parse will fail. From analysing this method usage, it looks like
this rev-parse is not needed.

Related-Prod: https://mirantis.jira.com/browse/PRODX-23489
Change-Id: I06adad433b0b3e0792848126297f4f65dd5117c0
diff --git a/src/com/mirantis/mk/Git.groovy b/src/com/mirantis/mk/Git.groovy
index 1426280..334bf01 100644
--- a/src/com/mirantis/mk/Git.groovy
+++ b/src/com/mirantis/mk/Git.groovy
@@ -34,7 +34,6 @@
             submoduleCfg: [],
             userRemoteConfigs: [[url: url, credentialsId: credentialsId, refspec: reference]]]
         )
-        sh(returnStdout: true, script: 'git rev-parse HEAD').trim()
     }
 }