infoschema: engines table improved

[morgo]

What problem does this PR solve?

The information_schema.engines table produced different output to SHOW ENGINES. This PR makes both show just "InnoDB" as the engine, which is more accurate.

What is changed and how it works?

Removed the non-innodb engines from information_schema.engines.

Check List

Tests

• Manual test (add detailed scripts or steps below)

This has no functional basis, so I've not written unit tests. But I can if you believe we should.

Code changes

• Minor changes

Side effects

• Breaking backward compatibility

It is unlikely, but a user could rely on the previous (incorrect) list of engines.

Related changes

• Need to be included in the release note
• Update documentation on information_schema.engines (it currently says this table is dummy data, but I would consider it accurate once this PR is pulled.)

[shenli]

LGTM

[shenli]

@coocood PTAL

[eurekaka]

LGTM. Any special reason that we have 2 separate hard-coded data sources for show and information_schema? e.g, dataForEngines and fetchShowEngines here. Should we convert show to select * from information_schema.xxx in the long run?

[eurekaka]

/run-all-tests

[shenli]

@eurekaka No special reason. We could merge them together.

[morgo]

@eurekaka I was wondering the same thing. In MySQL SHOW commands are aliases to information_schema.

There are also other SHOW + infoschema commands which are inconsistent, for example SHOW TABLE STATUS does not have the new meta data added in #7657

[jackysp]

LGTM