build: pin ChromeDriver version (#20940)

Since our version of Chromium is also pinned, a new ChromeDriver (that
drops support for our Chromium version) can cause random (and unrelated
to the corresponding changes) errors on CI.
This commit pins the version of ChromeDriver and it should now be
manually upgraded to a vrsion that is compatible with th currently used
Chromium version.

PR Close #20940

scripts/ci/env.sh

@@ -17,7 +17,7 @@ function  setEnvVar() {
   if [[ ${print} == "print" ]]; then
     echo ${name}=${value}
   fi
-  export ${name}=${value}
+  export ${name}="${value}"
 }
 
 # use BASH_SOURCE so that we get the right path when this script is called AND source-d
@@ -37,6 +37,7 @@ fi
 setEnvVar NODE_VERSION 8.9.1
 setEnvVar YARN_VERSION 1.0.2
 setEnvVar CHROMIUM_VERSION 499098 # Chrome 62 linux stable, see https://www.chromium.org/developers/calendar
+setEnvVar CHROMEDRIVER_VERSION_ARG "--versions.chrome 2.33"
 setEnvVar BAZEL_VERSION 0.8.1
 setEnvVar SAUCE_CONNECT_VERSION 4.4.9
 setEnvVar ANGULAR_CLI_VERSION 1.5.0-rc.2