[Preview 7] Fix debugger thread context validation after recent change

[kouvel]

• Port of Fix debugger thread context validation after recent change #55839 to preview 7
• Followup fix to Fix behavior of inlined NDirect methods with MulticoreJit #55185

Customer impact

• When a thread in a debuggee process remains in managed code for an extended duration without switching GC modes or hitting a GC poll, it may fail to suspend for the debugger
• This can result in a hang when attaching, breaking, or hitting a breakpoint
• A simple test case is shown in Fix debugger thread context validation after recent change #55839 (comment)

Regression?

• Yes, from 6.0 preview 6

Testing

• Manual test with a repro
• CI tests

Risk

Very low:

• The change reverts to previous behavior in the affected case