Fix handling of order 2 generators in MTC (#5747) #5472

Job	Run time
Cross compiler for s390x	27m 10s
Test in OpenBSD	8m 17s
testinstall - - ubuntu-latest	4m 17s
teststandard - - ubuntu-latest	19m 18s
testmanuals - - ubuntu-latest	5m 47s
testexpect testmockpkg testspecial test-compile testlibgap testkernel testworkspace - - ubuntu-latest	6m 45s
testpackages testinstall-loadall - - ubuntu-latest	25m 57s
makemanuals testmakeinstall - CONFIGFLAGS="--prefix=/tmp/gapprefix" NO_COVERAGE=1 - ubuntu-latest	5m 11s
teststandard - ABI=32 CONFIGFLAGS="" - ubuntu-20.04	18m 9s
testinstall - HPCGAP=yes ABI=64 - ubuntu-latest	7m 10s
testmockpkg testinstall - BOOTSTRAP_MINIMAL=yes - macos-latest	3m 18s
testbugfix - CONFIGFLAGS="--enable-memory-checking" - ubuntu-latest	26m 24s
testbuildsys testmockpkg testinstall - NO_COVERAGE=1 ABI=64 BUILDDIR=out-of-tree CONFIGFLAGS="--enable-valgrind" - ubuntu-latest	4m 17s
testbuildsys testmockpkg testinstall - NO_COVERAGE=1 ABI=32 BUILDDIR=out-of-tree CONFIGFLAGS="" - ubuntu-20.04	3m 42s
testinstall - JULIA=yes CONFIGFLAGS="--enable-debug --disable-Werror" - ubuntu-20.04	4m 32s
testmockpkg testinstall - - windows-2019	14m 52s
Send Slack notification on status change	2s
	3h 5m 8s

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