Revert Docsy card- and tabpane-shortcode style workarounds

[chalin]

#1027 introduced the following style workaround google/docsy@v0.4.0...grpc:grpc.io-docsy:grpc.io-upto-doccsy-0.4.0#diff-1f4d7b8618cd04fd8c5bf1b1dc08c5ae99ade3e2418c79d1e8f2acaa07a90923:

Undo this override once the original issue (google/docsy#1154) is fixed and merged into grpc.io-docsy.

[eugeneo]

@chalin Is this still relevant?

[chalin]

@eugeneo - yes it is still relevant.