Remove Unused Upgrade Code

[mitchelsellers]

Description of problem

DNN Platform upon upgrade at times will need to execute manual steps to perform the upgrade. This is all done as part of the installer component code. However, over time, this has resulted in the code growing substantially with each reelese.

Description of solution

For the past 5+ years an incremental upgrade pathway has been suggested for upgrade. Following this upgrade path users would do multiple upgrades PRIOR to upgrading to 9.x.

As such, in the 9.x platform, any manual upgrade steps that exist prior to 9.3.2 would be un-used as the prior 9.3.2 upgrade path would have already executed those steps.

To be safe, and considering that users do not always follow the upgrade path, I propose the removal of all manual upgrades steps prior to 7.4.2. This will support 4 individual hops back from the current recommendations. new installations are NOT impacted by this code.

Description of alternatives considered

We could leave this code, but the amount of bloat and maintenance benefit is huge.