[clang] [llvm] [MC] Make UseAssemblerInfoForParsing mostly true (PR #91082)

[Fangrui Song via llvm-commits]

MaskRay wrote:

> We started seeing a build time regression in our Clang toolchain builders on Mac, and I bisected to this commit:
> 
> 1. Build step took 1.7 hours in the last build before (clang -> build)
>    [luci-milo.appspot.com/ui/p/fuchsia/builders/prod/clang-mac-x64/b8747439072851399889/overview](https://luci-milo.appspot.com/ui/p/fuchsia/builders/prod/clang-mac-x64/b8747439072851399889/overview)
> 2. Build step took 2.5 hours in the first build after (clang -> build)
>    [luci-milo.appspot.com/ui/p/fuchsia/builders/prod/clang-mac-x64/b8747425464531858929/overview](https://luci-milo.appspot.com/ui/p/fuchsia/builders/prod/clang-mac-x64/b8747425464531858929/overview)

@gulfemsavrun  
Commit 245491a9f384e4c53421196533c2a2b693efaf8d (`[MC] Disable MCAssembler based constant folding for DwarfDebug`; independent of this patch) should have fixed the compile time regression. Might be worth testing the commit before and at 245491a9f384e4c53421196533c2a2b693efaf8d to see the time decrease.

https://github.com/llvm/llvm-project/pull/91082