fix(pingEndpoint): change build type to 'oss', use correct version

[bednar]

This PR fix the /ping endpoint:

• change build type from cloud2 to oss2
• use correct version for X-Influxdb-Version header

• Well-formatted commit messages
• Rebased/mergeable
• Tests pass
• http/swagger.yml updated (if modified Go structs or API)
• Signed CLA (if not already signed)

[williamhbaker]

Looks like the original PR on master: #21723 - with the exception of the swagger changes, which makes sense since we have kept the swagger in the 2.0 branch. The swagger changes appear consistent with influxdata/openapi#140.

Everything looks good to me, but would you mind adding an entry to the CHANGELOG? It's a pretty minor change but would still be good to document for the next release.

[bednar]

@wbaker85 thanks for review, the CHANGELOG.md is updated