Remove build optimization condition branch from ruby
Remove build optimization condition branch from ruby

Red Hat Enterprise Linux (RHEL) 5 reached end of extented life-cycle
support aka ELS by Red Hat in Nov 2020.

Partially porting from: https://github.com/chef/omnibus-software/pull/1088

Signed-off-by: Takuya Noguchi <b6ff22f4ae6fe3ca1371a0ef8d104f1c4bca551b@gmail.com>

gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab