MNT: increase timeout limits (limits on all form spinboxes), prevent aggressive navigation

[tangkong]

Description

• increase the limit on spinboxes generated from MultiInputFormDialog, in response to a request that set-value-step timeouts not be limited to 99s (we have very slow motors)
• navigate BACK to the parent page when creating a new check in SetValueStep
  • This negates the default behavior of StepPage, which selects new items when they are created.
  • Because SetValueStep initialized a row/new item without setting a PV, this resulted in extraneous navigation back to the parent page to set the PV, then back to the details to set the comparison information
  • Hacky but I'm too lazy to figure out a better way

Motivation and Context

Bug reports from @c-tsoi

How Has This Been Tested?

Interactively. Test suite still passes

Where Has This Been Documented?

This PR

Pre-merge checklist

• Code works interactively
• Code contains descriptive docstrings, including context and API
• New/changed functions and methods are covered in the test suite where possible
• Code has been checked for threading issues (no blocking tasks in GUI thread)
• Test suite passes locally
• Test suite passes on GitHub Actions
• Ran docs/pre-release-notes.sh and created a pre-release documentation page
• Pre-release docs include context, functional descriptions, and contributors as appropriate

[ZLLentz]

Briefly scrutinizing this: why is the parent's parent always the instance that owns the full tree?

[tangkong]

The SetValueStep widget is inside a QWidget container, which is itself inside a StepPage(PageWidget) widget. only those PageWidget classes can see the full tree

[tangkong]

I forgot about this. Merging now