[roll] Roll fuchsia [ffx] Turn docs/examples/strict into a runnable test

Make docs/examples/strict/strict.py run as an automated test on CQ/CI
to prevent it from rotting.

- Modified strict.py to read the SSH private key path from the
  FUCHSIA_SSH_KEY environment variable if present, falling back to
  resolving the default path via `os.path.expanduser`.
- Declared docs/examples/strict files as a host_test_data target in
  tests/e2e/python/BUILD.gn and added them as test dependencies.
- Added test_strict_example_script E2E test to ffx_strict.py. It
  dynamically locates the toolchain directory containing the test data,
  sets up target and SSH details, and executes strict.py in a
  temporary working directory to avoid writing log files to read-only paths.

Original-Original-Bug: 376082773
Test: fx test ffx_strict_host_tool_e2e_test --e2e --test-filter test_strict_example_script

TAG=agy
CONV=bc9d073c-6d3f-42d3-bc40-b23921515a90

Original-Original-Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1666376
Original-Original-Revision: 5d53036fe9c68a4250700f5c54459384fff812ea
GitOrigin-RevId: 02e7c7041177d36e6edb7078a5a1675ebaac5f66
Change-Id: Id10c2d7a30b1e7136e32e8d74f28808d00c12765
Reviewed-on: https://fuchsia-review.googlesource.com/c/integration/+/1665075
Cr-Commit-Position: refs/heads/main@{#195175}