[SPARK-25673][BUILD] Remove Travis CI which enables Java lint check

## What changes were proposed in this pull request?

#12980 added Travis CI file mainly for linter because we disabled Java lint check in Jenkins.

It's enabled as of #21399 and now SBT runs it. Looks we can now remove the file added before.

## How was this patch tested?

N/A

Closes #22665

Closes #22667 from HyukjinKwon/SPARK-25673.

Authored-by: hyukjinkwon <[email protected]>
Signed-off-by: hyukjinkwon <[email protected]>

Author: HyukjinKwon