merge bta_ag_create_pending_sco into bta_ag_create_sco and bta_ag_sco_conn_rsp

bta_ag_create_pending_sco() has many lines of code that is identical to the one in bta_ag_create_sco(). Also,
bta_ag_create_pending_sco(xx, true) is only used in bta_ag_create_sco();
bta_ag_create_pending_sco(xx, false) is only used in bta_ag_sco_conn_rsp().
So remove bta_ag_create_pending_sco() function

Bug: 323264322
Flag: Exempt, moving code, no logical change
Test: atest net_test_bta
Change-Id: I301b20f423e525c845c21e7108e0afddd5e87316