Reduce cache timeouts to ensure faster builds on timeout. (#9619)

The current timeouts are too long, and mean that if the GitHub cache
decides to act up, jobs get bogged down for 15min at a time. This has
happened 2-3 times already this week -- a tiny fraction of our total
workflows but really annoying when it happens to you. We can do better.

Installing deps on cache miss takes about ~4min, so it's not worth
waiting more than 4min for the deps cache. The black and mypy caches
save 1 and 2min, respectively, so wait only up to that long to download
them.

.github/actions/poetry_setup/action.yml

@@ -41,7 +41,7 @@ runs:
       id: cache-pip
       name: Cache Pip ${{ inputs.python-version }}
       env:
-        SEGMENT_DOWNLOAD_TIMEOUT_MIN: "15"
+        SEGMENT_DOWNLOAD_TIMEOUT_MIN: "4"
       with:
         path: |
           ~/.cache/pip
@@ -69,7 +69,7 @@ runs:
     - uses: actions/cache@v3
       id: cache-poetry
       env:
-        SEGMENT_DOWNLOAD_TIMEOUT_MIN: "15"
+        SEGMENT_DOWNLOAD_TIMEOUT_MIN: "4"
         WORKDIR: ${{ inputs.working-directory == '' && '.' || inputs.working-directory }}
       with:
         path: |