Change Max Import Size limit setting to be disabled by default

Recently we (Quality) noticed today that a project import max size limit of 50mb is being enforced by default now on our omnibus based test environments. This appears to have added within the last week.

For Omnibus self managed installs typically we suggest for these limits to be disabled (see #223718 (comment 382174618) for a similar issue) and for users to opt in rather than get stung as each customer will likely always have unique needs and have to customise limits anyways. For example any customer now wanting to run GPT will absolutely hit this issue and make the process more complicated.

Looking around I can see Infra were stung with this on .com last week and tweaked it back accordingly but I can’t find the specific issue or MR for the change itself (although I found the MR to introduce the setting itself).

For the reasons about this should be removed before it makes it into a release.