perf-stream-locked-section: advertise the right version key in the help
As the v3 format is still experimental, its key is "v3-exp". The help text was
not pointing that out.
(we also fix `perf::stream-generate` in the process)
Same with share-safe
$ echo "[format]" >> $HGRCPATH
$ echo "use-share-safe = True" >> $HGRCPATH
$ cd $TESTTMP
$ hg init myrepo
$ cd myrepo
$ cat > .hg/hgrc <<EOF
> [extensions]
> sparse=
> EOF
$ echo a > show
$ echo x > hide
$ hg ci -Aqm 'initial'
Regression test: checks that this command correctly locks the store
before updating the store [requirements] config.
$ hg up -q 0
$ hg debugsparse --include 'hide'