chore: tweak kokoro config (via synth) (#129)

* chore(python): skip docfx in main presubmit

* chore(python): skip docfx in main presubmit

* fix: properly template the repo name

Source-Author: Bu Sun Kim <8822365+busunkim96@users.noreply.github.com>
Source-Date: Fri Jan 8 10:32:13 2021 -0700
Source-Repo: googleapis/synthtool
Source-Sha: fb53b6fb373b7c3edf4e55f3e8036bc6d73fa483
Source-Link: https://github.com/googleapis/synthtool/commit/fb53b6fb373b7c3edf4e55f3e8036bc6d73fa483

* chore: add missing quotation mark

Source-Author: Bu Sun Kim <8822365+busunkim96@users.noreply.github.com>
Source-Date: Mon Jan 11 09:43:06 2021 -0700
Source-Repo: googleapis/synthtool
Source-Sha: 16ec872dd898d7de6e1822badfac32484b5d9031
Source-Link: https://github.com/googleapis/synthtool/commit/16ec872dd898d7de6e1822badfac32484b5d9031
diff --git a/.trampolinerc b/.trampolinerc
index 995ee29..c7d663a 100644
--- a/.trampolinerc
+++ b/.trampolinerc
@@ -18,12 +18,14 @@
 required_envvars+=(
     "STAGING_BUCKET"
     "V2_STAGING_BUCKET"
+    "NOX_SESSION"
 )
 
 # Add env vars which are passed down into the container here.
 pass_down_envvars+=(
     "STAGING_BUCKET"
     "V2_STAGING_BUCKET"
+    "NOX_SESSION"
 )
 
 # Prevent unintentional override on the default image.