Disable the generation of the Confluence upgrade recovery file by default

Problem statement

When Confluence is upgraded, a pre and post-upgrade recovery file are generated by default and can sometimes result in an OOM error or a long upgrade pause to occur. This is not ideal for large instances and administrators have to disable this by adding the following argument in the setenv file.

-Dconfluence.upgrade.recovery.file.enabled=false

Suggestion

As the pre and post-upgrade recovery files can't be used to restore an instance's data, it serves little to no purpose to our users. It is also troublesome for administrators to constantly add this parameter in with every upgrade attempt (especially when the upgrade is performed many times in case of any upgrade failures).

Therefore, it would be great if the parameter below could be added to the Java options by default or if the recovery files are simply not generated at all.

-Dconfluence.upgrade.recovery.file.enabled=false