[SPARK-23169][INFRA][R] Run lintr on the changes of lint-r script and .lintr configuration

[HyukjinKwon]

What changes were proposed in this pull request?

When running the run-tests script, seems we don't run lintr on the changes of lint-r script and .lintr configuration.

How was this patch tested?

Jenkins builds

[HyukjinKwon]

This was tested:

1. fe59c8a intentionally added some changes in .lintr and lint-r to see if triggers the lint: https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/86430/console

2. Added the detection logic to check if it triggers the lintr: 12789c7 - https://amplab.cs.berkeley.edu/jenkins/job/SparkPullRequestBuilder/86431/console

3. Reverted the change of 1. back to leave only 2. change in this PR.

cc @felixcheung and @JoshRosen, could you take a look please?

[SparkQA]

Test build #86430 has finished for PR 20339 at commit fe59c8a.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #86431 has finished for PR 20339 at commit 12789c7.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[SparkQA]

Test build #86432 has finished for PR 20339 at commit 5ca17ac.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

[HyukjinKwon]

Merged to master.

[HyukjinKwon]

Thanks for reviewing this @felixcheung and @srowen.