Revert [clang] Handle templated operators with reversed arguments and [STLExtras] Undo C++20 hack

[usx95]

This breaks C++20 build of LLVM by clang 17 and earlier.
Next steps should be reduce error to a warning for https://godbolt.org/z/s99bvq4sG
b100ca6 or similar should be reapplied after the bug fix reached clang-18.

[nico]

Looks like the revert broke tests: http://45.33.8.238/linux/121332/step_7.txt

Please take a look.

[dyung]

This revert seems to have broken quite a few build bots with the test failure @nico mentioned. Can you please look into this so we can get the bots green again?

• https://lab.llvm.org/buildbot/#/builders/164/builds/45362
• https://lab.llvm.org/buildbot/#/builders/188/builds/36986
• https://lab.llvm.org/buildbot/#/builders/197/builds/10402
• https://lab.llvm.org/buildbot/#/builders/245/builds/15680
• https://lab.llvm.org/buildbot/#/builders/258/builds/8447
• https://lab.llvm.org/buildbot/#/builders/121/builds/35809
• https://lab.llvm.org/buildbot/#/builders/230/builds/20289
• https://lab.llvm.org/buildbot/#/builders/91/builds/20979
• https://lab.llvm.org/buildbot/#/builders/109/builds/76025
• https://lab.llvm.org/buildbot/#/builders/36/builds/39047
• https://lab.llvm.org/buildbot/#/builders/54/builds/6960
• https://lab.llvm.org/buildbot/#/builders/275/builds/38
• https://lab.llvm.org/buildbot/#/builders/139/builds/52005
• https://lab.llvm.org/buildbot/#/builders/216/builds/29174

[usx95]

Apologies. I have reverted the missed tests in a876385
The build bots should be fine now.