software/theia: prepend our PATH entries before gowork's

gowork include gcc's location, which can be /usr/bin when system gcc was
selected.
3 jobs for feat/theia-standalon-slapos in 0 seconds
Status Job ID Name Coverage
  External
canceled SlapOS.SoftwareReleases.IntegrationTest-Jerome-743

36:44:55

failed SlapOS.SoftwareReleases.IntegrationTest-Jerome-743

09:23:42

canceled SlapOS.SoftwareReleases.IntegrationTest-Jerome-743

14:47:04