chore: Enable token caching for e2e tests (#302)

## Motivation

To reduce token requests we decided to enable use the same config
between tests.

Author: daniel-zelazny

test/docker/Dockerfile.e2e

@@ -9,6 +9,5 @@ WORKDIR /sloctl
 COPY ./test ./test
 COPY --from=sloctl-e2e-test-bin /usr/bin/sloctl /usr/bin/sloctl
 
-ENV SLOCTL_NO_CONFIG_FILE=true
 # Required for bats pretty printing.
 ENV TERM=linux