Fix build break from generating robo test code coverage

Use absolute path for LOCAL_INSTRUMENT_SOURCE_DIRS, because Jacoco fail
to get the source code path to parse the code coverage.

Test step:
1. tapas RunLauncherRoboTests
2. make -j30 dist (Make sure RunLauncherRoboTests does not break)
3. make -j30 RunLauncherRoboTests-jacoco dist
4. See the coverage report

Bug: 149001617
Change-Id: If82a839ae52c20c7eb269090976de05fa5d462c4