[CALCITE-4646] Bump Jetty version to 9.4.42.v20210604 (Istvan Toth)
Updating jetty.version causes several SPENGO tests to fail
due to a breaking change in Jetty. The threads created by
Jetty no longer run as the Subject Jetty was started as.
1. Add new custom ThreadFactrory to obtain the old
behavior and overcome failures.
2. Copy most of org.apache.calcite.util.Sources to Avatica,
and use them in tests.
3. Remove illegal leading slash in the file paths to avoid
test failures on Windows.
8 files changed