pgsql: Small refactoring around ExecCreateTableAs().

Small refactoring around ExecCreateTableAs().

Since commit 4b74ebf726, the refresh logic is used to populate
materialized views, so we can simplify the error message in
ExecCreateTableAs().

Also, RefreshMatViewByOid() is moved to just after
create_ctas_nodata() call to improve code readability.

Author: Yugo Nagata
Discussion: https://postgr.es/m/20240802161301.d975daca9ba7a706fa05ecd7@sraoss.co.jp

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/7926a9a80f6daf0fcc1feb1bee5c51fd001bc173

Modified Files
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src/backend/commands/createas.c | 34 +++++++++++++++++-----------------
1 file changed, 17 insertions(+), 17 deletions(-)