installd: Skip profile preparation if primary.prof does not exist

If the primary.prof does not exist in .dm file, the profman here will
create an empty reference profile, which will slow down the dex2oat.

And, the profman process is expensive (about hundreds of
milliseconds), we should avoid it if the primary.prof does not exist.

Bug: 204415663

Change-Id: I8ed16b2090659b2541c71b748f7e1a1552fa1a5e
Signed-off-by: Yang Tianping <yangtianping@oppo.com>