Update passing of GERRIT_BRANCH parameter

	- Use name GERRIT_PARENT_BRANCH for transmission to avoid
	  Gerrit Trigger reserved param name

	- Enable usage in env child job (reverts a454611e04c5eff13b75dfd5a4d9e958e6ae5dec)

Related: PROD-29251

Change-Id: I90d8c739bb0aadbd3a63a7b6246f4b94efb71cb5
diff --git a/test-salt-formulas-pipeline.groovy b/test-salt-formulas-pipeline.groovy
index fee1e46..2bfdc7d 100644
--- a/test-salt-formulas-pipeline.groovy
+++ b/test-salt-formulas-pipeline.groovy
@@ -15,6 +15,7 @@
 def defaultGitUrl = env.DEFAULT_GIT_URL ?: null
 def slaveNode = env.SLAVE_NODE ?: 'virtual'
 def saltVersion = env.SALT_VERSION ?: ""
+gerritBranch = env.GERRIT_BRANCH
 def dockerLib = new com.mirantis.mk.Docker()
 
 def checkouted = false
@@ -60,7 +61,7 @@
     [$class: 'StringParameterValue', name: 'DEFAULT_GIT_URL', value: defaultGitUrl],
     [$class: 'StringParameterValue', name: 'SALT_OPTS', value: SALT_OPTS],
     [$class: 'StringParameterValue', name: 'SALT_VERSION', value: SALT_VERSION],
-    [$class: 'StringParameterValue', name: 'GERRIT_BRANCH', value: GERRIT_BRANCH]
+    [$class: 'StringParameterValue', name: 'GERRIT_PARENT_BRANCH', value: gerritBranch]
   ]
 }