Resolve "Jaeger didn't update automatically"
What does this Merge Request do?
This MR adds the jaeger-update Makefile target which allows jaeger to be automatically updated. We also add optional support for jaeger 1.21.0 for those that wish to test.
Merge Request checklist
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Tests added for new functionality. If not, please raise Issue to follow-up. 
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This change is backward compatible. If not, please include steps to communicate to our users. 
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Documentation added/updated, if needed. 
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gdk doctortest added, if needed.
Closes #1132 (closed)