refac(ci): improve build time

[juancarlostong]

Summary

Optimizations to the 'Integration tests' triggering build:

• added merge_mode: replace, trigger job only needs to run shell script, so just do that and nothing else.
• added cache: false, caching is used for some *-sdk, this disables it for the 'Integration tests' triggering build since it is not needed.
• replaced after_success: skip with after_success: travis_terminate 0, this avoids running srcclr which saves 18-30s from build time.

[coveralls]

Coverage decreased (-0.007%) to 98.027% when pulling 22fa48b on jctong/improve_build_time into c83981b on master.

[coveralls]

Coverage remained the same at 97.987% when pulling 55acdb9 on jctong/improve_build_time into 42445df on master.

[mikeproeng37]

lgtm