pgsql: pg_createsubscriber: Remove failover replication slots on subscr

pg_createsubscriber: Remove failover replication slots on subscriber

After running pg_createsubscriber, these replication slots have no use
on subscriber, so drop them.

Author: Euler Taveira <euler.taveira@enterprisedb.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Discussion: https://www.postgresql.org/message-id/776c5cac-5ef5-4001-b1bc-5b698bc0c62a%40app.fastmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/81d20fbf7a03f5e385700c90aec883c96b32ddc6

Modified Files
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doc/src/sgml/ref/pg_createsubscriber.sgml          |  9 ++++
src/bin/pg_basebackup/pg_createsubscriber.c        | 49 +++++++++++++++++++++-
src/bin/pg_basebackup/t/040_pg_createsubscriber.pl | 20 ++++++++-
3 files changed, 76 insertions(+), 2 deletions(-)