add manual flags and remove 156-subapps/_shinyjster.R

[schloerke]

Related https://github.com/rstudio/shinycoreci/pull/25

https://github.com/schloerke/shinyjster/pull/32 allows for shinyjster::run_jster("156-subapps") with 156-subapps/index.Rmd.

35 apps are flagged to be manually tested

Questions on apps:

• [x] Where is the 140-comprehensive-selectize app?
  • To be removed
• [x] May we not manually test 169-prerender as it is difficult to execute?
  • Must provide a script that can be run locally.
  • shinycoreci::test_shinyjster(apps = "169-prerender")

I don’t mind making an extra testing function to test app 169-prerender using shinyjster (for non-hosted locations, ex: cloud / IDE / RSP), but 169-prerender can not be tested on deployed locations.