Pre-start uses `chpst` instead of `su`
Pre-start uses `chpst` instead of `su`

[#161936173]

Signed-off-by: Andrew Garner <0ff7b0612175403deb65f6983ad8d057f9d25555@pivotal.io>

cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release,cloudfoundry/cf-mysql-release