fix(ci): update test utils to write temp files to directory outside of `/tmp` for CI

[timwu20]

Changes

• runs unit-tests and integration-tests github workflows using a CI=buildjet env variable
• introduces code that checks this environment variable, and writes temp files to separate unpruned directory when running in CI
• dot package tests are only flakey on CI

Tests

• ensure all workflows pass successfully

Issues

• closes #4035

[dimartiro]

Can we close it since we already merged https://github.com/ChainSafe/gossamer/pull/4037 ?