Draft: CI: Update fedora base image to f40

See commits

Needs:

• !5432 (merged)
• GIR file have new fields and must be updated
• clang warning in vulkan video code !5996 (merged)
• Documentation build issues
  • Missing core glib symbols from upstream devhelp
  • Add symbols (for plugins which are dynamically generated or were previously not built on CI) to symbol list
• Failing unit tests
  • gst-plugins-bad.elements_dash_mpd.dash_mpdparser_xlink_period
  • gst-plugins-bad.elements_netsim.netsim_stress_delayed
  • gst-plugins-good.elements_mpegaudioparse.test_parse_gapless_and_skip_padding_samples
  • gst-plugins-bad.validate.autovideoconvert.renegotiate
• Add missing OpenSSL valgrind supressions (see https://stackoverflow.com/questions/21532371/memory-leak-in-openssl-function-evp-pkey-keygen)
• Valgrind failures
• Re-enable GST_WERROR: "true"