All clang docker images here are based on Debian 11 (Bullseye) but now we're moving to Debian 12 (Bookworm) primarily to use the recent versions of Cmake >= 3.20 to use CXX_STANDARD=23 for some tests ([doc](https://cmake.org/cmake/help/latest/prop_tgt/CXX_STANDARD.html))
Closes#36810
PiperOrigin-RevId: 640688681
This commit upgrades gRPC to protobuf v25.0 and makes some fixes to
account for upb changes. One major change is that upb has been merged
into the protobuf repo, so we can now drop the separate `@upb`
dependency. Another is that `.upb.c` files no longer exist and there are
new `.upb_minitable.h` and `.upb_minitable.c` files. The longer
filenames exceeded a Windows restriction, so to work around that I
renamed the `upb-generated` directory to just `upb-gen`, and likewise
for `upbdefs-generated`.
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* nit in python interop dockerfile
* address TODO in prepare_ccache_symlinks_rc
* enable ccache for C# and ruby distribtest jobs
* use debian11 instead of bullseye consistently
Jessie has a line that looks like this, now-a-days, so the regex is no
longer matching:
deb http://security.debian.org/debian-security jessie/updates main
But because that line was changed, downloads are also working correctly
out-of-the-box. The sed was originally added in #18530.