Maintainer updates for testing, gdb, semihosting and plugins This collects up a number of fixes across my various maintainer trees. There will be a longer plugins related one coming later but I wanted to turn these around first. The update to bookworm was delayed from the last release but I've now "solved" that by moving sh4 and alpha into a legacy container stuck on bullseye. I've also taken the opportunity to rationalise our zoo of containers to better sync up with what we actually use on gitlab. The following still need review: plugins: Remove an extra parameter tests/docker: upgrade debian-all-test-cross to bookworm tests/docker: use debian-all-test-cross for sparc64 tests/docker: use debian-all-test-cross for riscv64 tests/docker: use debian-all-test-cross for mips tests/docker: use debian-all-test-cross for mips64 tests/docker: use debian-all-test-cross for m68k tests/docker: use debian-all-test-cross for hppa tests/docker: use debian-all-test-cross for power tests/docker: move sh4 to use debian-legacy-test-cross tests/docker: use debian-legacy-test-cross for alpha gitlab: split alpha testing into a legacy container