stream-clone: stop getting the file size of all file in v3
The point of v3 is to do less work in the locked section. It was currently not
the case.
This significantly boost performance. The following number comes from a large
private repository using perf::stream-locked-section:
base-line: 35.03 seconds
this-change: 24.50 seconds (-30%)
# Files that just need to be migrated to the formatter.
# Do not add new files here!
mercurial/cext/manifest.c
mercurial/cext/osutil.c
# Vendored code that we should never format:
syntax: glob
contrib/python-zstandard/**.c
contrib/python-zstandard/**.h
hgext/fsmonitor/pywatchman/**.c
mercurial/thirdparty/**.c
mercurial/thirdparty/**.h
mercurial/pythoncapi_compat.h