JIT: Fix gtGetClassHandle with commas (#87313)
gtGetClassHandle has comments about "Tunnel through commas", yet several
of the cases then do not actually use the effective value, resulting in
possible asserts when this function is passed a comma.
Fixes an issue I saw in #87265 when morph invokes gtFoldTypeCompare for
the following IR:
```
fgMorphTree BB19, STMT00013 (before)
[000045] -ACXG------ * JTRUE void
[000044] -ACXG------ \--* NE int
[000623] -ACXG------ +--* COMMA ref
[000622] DA--------- | +--* STORE_LCL_VAR ref V29 tmp18
[000621] ----------- | | \--* LCL_FLD ref V07 loc3 [+0]
[000041] -ACXG------ | \--* CALL nullcheck ref Microsoft.Extensions.Configuration.Test.ConfigurationProviderTestBase+TestKeyValue:get_AsArray():System.String[]:this
[000620] -A--------- this | \--* COMMA ref
[000619] DA--------- | +--* STORE_LCL_VAR ref V30 tmp19
[000618] ----------- | | \--* LCL_FLD ref V07 loc3 [+8]
[000617] ----------- | \--* LCL_VAR ref V30 tmp19
[000043] ----------- \--* CNS_INT ref null
```