Remove antlr auto build with build/test script

[Danieladu]

We added antlr4ts-cli into dependency and would auto build g4 grammar when build and test script is executed. But antlr4ts-cli script depends on JAVA environment. the reference is here:
https://www.npmjs.com/package/antlr4ts-cli

So, remove the auto build of antlr, and instead, keep the antlr script, user can still run the script manually with local JAVA environment.

[coveralls]

Pull Request Test Coverage Report for Build 132831

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 9 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.07%) to 80.286%

---

Files with Coverage Reduction	New Missed Lines	%
libraries/botframework-streaming/src/webSocket/webSocketTransport.ts	2	80.65%
libraries/botframework-streaming/src/webSocket/webSocketServer.ts	7	66.67%

Totals
Change from base Build 132665:	-0.07%
Covered Lines:	12691
Relevant Lines:	15092

---

💛 - Coveralls