Unflip strict run feature flag (#519)

## Summary

Turning the feature off after finding some issues when running against
`devbox-examples`.

Author: ipince

internal/boxcli/featureflag/strict_run.go

@@ -4,4 +4,4 @@ package featureflag
 // runs the script in the environment returned by `nix print-dev-env`. This means the
 // environment is much more "strict" or "pure", since it will _not_ include parts of
 // the host's environment like `devbox shell` does.
-var StrictRun = enabled("STRICT_RUN")
+var StrictRun = disabled("STRICT_RUN")