pgsql: Remove some useless code

Remove some useless code

In commit 8b08f7d4820f I added member relationId to IndexStmt struct.
I'm now not sure why; DefineIndex doesn't need it, since the relation
OID is passed as a separate argument anyway.  Remove it.

Also remove a redundant assignment to the relationId argument (it wasn't
redundant when added by commit e093dcdd285, but should have been removed
in commit 5f173040e3), and use relationId instead of stmt->relation when
locking the relation in the second phase of CREATE INDEX CONCURRENTLY,
which is not only confusing but it means we resolve the name twice for
no reason.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e439c6f0c3ddc6e4b71922ec326cb796c2885656

Modified Files
--------------
src/backend/commands/indexcmds.c   | 5 ++---
src/backend/nodes/copyfuncs.c      | 1 -
src/backend/nodes/equalfuncs.c     | 1 -
src/backend/nodes/outfuncs.c       | 1 -
src/backend/parser/gram.y          | 2 --
src/backend/parser/parse_utilcmd.c | 1 -
src/include/nodes/parsenodes.h     | 1 -
7 files changed, 2 insertions(+), 10 deletions(-)