executor: Add support for placement in SHOW CREATE TABLE

[sylzd]

What problem does this PR solve?

results like that:

CREATE TABLE t1 (a int);
SHOW CREATE TABLE t1;
-->
CREATE TABLE `t1` (
  `a` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

CREATE TABLE t2 (a int) PLACEMENT POLICY='acdc';
SHOW CREATE TABLE t2;
-->
CREATE TABLE `t2` (
  `a` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin /*T![placement] PLACEMENT POLICY=`acdc` */;

ALTER DATABASE test DEFAULT PLACEMENT POLICY=`acdc`;
CREATE TABLE t3 (a int);
SHOW CREATE TABLE t3;
-->
CREATE TABLE `t3` (
  `a` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin /*T![placement]  PLACEMENT POLICY=`acdc` */;

ALTER TABLE t3 PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-east-2,us-west-1,us-west-2";
SHOW CREATE TABLE t3;
-->
CREATE TABLE `t3` (
  `a` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin /*T![placement] PRIMARY_REGION="us-east-1" REGIONS="us-east-1,us-east-2,us-west-1,us-west-2" */;

Issue Number: related to #26581

What is changed and how it works?

What's Changed:
executor/show.go

How it Works:

Check List

Tests

• Unit test
• Integration test

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• AilinKid
• xhebox

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[sylzd]

/run-check_dev_2

[sylzd]

/run-check_dev_2

[AilinKid]

Rest LGTM

[sylzd]

syntax ALTER DATABASE test DEFAULT PLACEMENT POLICY=`x`; haven't been implemented yet.

[AilinKid]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 0a78aa6

[ti-chi-bot]

@sylzd: Your PR was out of date, I have automatically updated it for you.

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/run-all-tests

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