net/opensips: Update 2.2.3 -> 2.2.6

Port changes:

• Change to DISTVERSION
• Add USERS/GROUPS and corresponding entries in UIDs/GIDs
• Add USE_RC_SUBR
• Change MYSQL_USE=MYSQL=client -> MYSQL_USES=mysql:client
• Remove unnecessary +=
• Add pkg-message
• Change WWW to https

PR: 226667
Submitted by: Euan Thoms <euan@potensol.com> (maintainer)