mon: Optimized EC clean_temps needs to permit primary change

mon: Optimized EC clean_temps needs to permit primary change

Optimized EC pools were blocking clean_temps from clearing pg_temp
when up == acting but up_primary != acting_primary because optimized
pools sometimes use pg_temp to force a change of primary shard.

However this can block merges which require the two PGs being
merged to have the same primary. Relax clean_temps to permit
pg_temp to be cleared so long as the new primary is not a
non-primary shard.

Signed-off-by: Bill Scales <bill_scales@uk.ibm.com>
(cherry picked from commit ce53276191e60375486f75d93508690f780bee21)