Merge bitcoin/bitcoin#27012: ci: Print iwyu patch in git diff format

fa6986a66b ci: Print iwyu patch in git diff format (MarcoFalke)

Pull request description:

  Seems more dev friendly to also have a patch to copy-paste

ACKs for top commit:
  hebasto:
    ACK fa6986a66b, tested on Ubuntu 22.04 locally.
  fanquake:
    ACK fa6986a66b - did not test but example CI output looks ok.
  stickies-v:
    utACK fa6986a66b

Tree-SHA512: 7cfd8584bf12e03c28af23f4712c6bcafd648d87ddb92788b9cd35455b2db49f4bd4aef8ad4711f75c7f11ad2bb2492c2eb6044007086c20e36016575c060603

ci/test/06_script_b.sh

@@ -75,7 +75,12 @@ if [ "${RUN_TIDY}" = "true" ]; then
           " src/util/syserror.cpp"\
           " src/util/threadinterrupt.cpp"\
           " src/zmq"\
-          " -p . ${MAKEJOBS} -- -Xiwyu --cxx17ns -Xiwyu --mapping_file=${BASE_BUILD_DIR}/bitcoin-$HOST/contrib/devtools/iwyu/bitcoin.core.imp"
+          " -p . ${MAKEJOBS}"\
+          " -- -Xiwyu --cxx17ns -Xiwyu --mapping_file=${BASE_BUILD_DIR}/bitcoin-$HOST/contrib/devtools/iwyu/bitcoin.core.imp"\
+          " |& tee /tmp/iwyu_ci.out"
+  export P_CI_DIR="${BASE_ROOT_DIR}/src"
+  CI_EXEC "python3 ${DIR_IWYU}/include-what-you-use/fix_includes.py --nosafe_headers < /tmp/iwyu_ci.out"
+  CI_EXEC "git --no-pager diff"
 fi
 
 if [ "$RUN_SECURITY_TESTS" = "true" ]; then