Assert hit in leakwheel running under full pgo

[AndyAyersMS]

complus_readytorun=0
complus_tc_quickjitforloops=1
complus_tieredpgo=1

corerun.exe GC\Scenarios\LeakWheel\leakwheel\leakwheel.dll
...
Assert failure(PID 12556 [0x0000310c], Thread: 13816 [0x35f8]): 
    Assertion failed 'block->bbWeight > BB_ZERO_WEIGHT' 
    in 'DefaultNamespace.LeakWheel:RunGame():bool:this' 
    during 'Optimize layout' (IL size 104)

    File: C:\repos\runtime1\src\coreclr\jit\fgdiagnostic.cpp Line: 2796

repro is somewhat intermittent, but not that hard to see.

[AndyAyersMS]

This is happening in the nighty PGO CI testing, eg this run.

We end up with negative block weights, which is not good.

*************** In fgReorderBlocks()
...
Setting edge weights for BB29 -> BB36 to [-0.09876383 .. -0.09876383]
Added an unconditional jump to BB31 after block BB29

After this change in fgReorderBlocks the BB graph is:
-----------------------------------------------------------------------------------------------------------------------------------------
BBnum BBid ref try hnd preds           weight      IBC  lp [IL range]     [jump]      [EH region]         [flags]
-----------------------------------------------------------------------------------------------------------------------------------------
BB01 [0047]  1                             1        22    [???..???)                                     keep i internal IBC 
BB02 [0000]  1       BB01                  1        22    [000..01D)-> BB12 ( cond )                     i hascall idxlen new[] newobj IBC 
BB08 [0024]  2       BB02,BB35             9.68    213    [000..000)-> BB09 ( cond )                     i internal idxlen bwd bwd-target IBC 
BB10 [0026]  1       BB08                  9.68    213    [000..000)-> BB12 ( cond )                     i internal idxlen bwd IBC 
BB35 [0051]  1       BB10                  9.68    213    [???..???)-> BB08 (always)                     internal IBC 
BB19 [0035]  3       BB09,BB15,BB18        1        22    [000..000)-> BB31 ( cond )                     i internal hascall gcsafe new[] newobj IBC 
BB24 [0001]  2       BB19,BB29           37659. 828491    [01D..040)-> BB28 ( cond )                     i hascall gcsafe bwd bwd-target IBC 
BB29 [0003]  1       BB24                37659. 828491    [054..060)-> BB24 ( cond )                     i bwd IBC 
BB36 [0052]  1       BB29                -0.0045      0    [???..???)-> BB31 (always)                     internal IBC 

[JulieLeeMSFT]

Removed untriaged label since we need to fix this assert in .NET 6.