fix: remove TS compile step for linked plugins

[cristiand391]

Reverts #517

oclif/core now uses ts-node to compile linked TS plugins at runtime so this compile step in plugins link is no longer needed.
oclif/core#650
@W-12702335@

[mshanemc]

QA notes:

[in plugin/plugins] sfdx plugins:link .

I put a console.log statement in the local copy of plugins:link to make sure it hit that version.

then I deleted the /lib folder from plugin org and ran

[in plugin-org] sfdx plugins:link .

[mshanemc]

disregard previous QA notes. Tested with the current CLI rc, which has the newer oclif/core, and this works fine.