Add join clause on srvid when joining with powa_statements.

[anayrat]

Several queries are built from powa_getdata_detailed_db by passing srvid. Later we join with powa_statements but join on srvid was missing which often lead to a seqscan on powa_statements.

Thanks to join on srvid we can use powa_statements PK.

[rjuju]

Nice catch, this should bring yet more speedup!

Thanks a lot @anayrat !