Custom timeout configuration for Omnibus Upgrades

Proposal

During a GitLab version upgrade, the packaged PostgreSQL automatic version upgrade can fail due to timeouts. The current solution is to manually upgrade PostgreSQL by running gitlab-ctl pg-upgrade with the underlying command --timeout.

Similar to the way users can set the timeout option for gitlab-ctl pg-upgrade, this proposal is to add a configurable option (possibly on the gitlab.rb) so the GitLab upgrade process can set the timeout option for PostgreSQL automatic upgrades and avoid manual upgrades.

Feature requested by a premium customer on this support ticket (internal)