chore(telemetry): enable telemetry by default

[mabdinur]

Description

Enables telemetry collection when an application is run with ddtrace-run.

Checklist

• [x] Title must conform to conventional commit.
• [x] Add additional sections for feat and fix pull requests.
• [x] Ensure tests are passing for affected code.
• [x] Library documentation and/or Datadog's documentation site is updated. Link to doc PR in description.

Motivation

Collect tracer configurations.

Design

Starts a telemetry writer which sends a payload of tracer configuration to the datadog agent. As of now one event is sent on application startup and another is sent when an application terminates.

Testing strategy

Ensure telemetry test suite passes in ci.

Relevant issue(s)

Testing strategy

Reviewer Checklist

• [ ] Title is accurate.
• [ ] Description motivates each change.
• [ ] No unnecessary changes were introduced in this PR.
• [ ] PR cannot be broken up into smaller PRs.
• [ ] Avoid breaking API changes unless absolutely necessary.
• [ ] Tests provided or description of manual testing performed is included in the code or PR.
• [ ] Release note has been added for fixes and features, or else changelog/no-changelog label added.
• [ ] All relevant GitHub issues are correctly linked.
• [ ] Backports are identified and tagged with Mergifyio.
• [ ] Add to milestone.

[codecov-commenter]

Codecov Report

Merging #4003 (15f2d01) into 1.x (2340f5d) will increase coverage by 0.14%. The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              1.x    #4003      +/-   ##
==========================================
+ Coverage   79.09%   79.23%   +0.14%     
==========================================
  Files         717      717              
  Lines       56487    56487              
==========================================
+ Hits        44678    44758      +80     
+ Misses      11809    11729      -80     

Impacted Files	Coverage Δ
ddtrace/bootstrap/sitecustomize.py	67.41% <100.00%> (+1.12%)	:arrow_up:
ddtrace/contrib/cassandra/session.py	87.84% <0.00%> (+1.10%)	:arrow_up:
ddtrace/internal/telemetry/writer.py	79.69% <0.00%> (+34.58%)	:arrow_up:
ddtrace/internal/telemetry/data.py	97.36% <0.00%> (+42.10%)	:arrow_up:
ddtrace/internal/packages.py	95.00% <0.00%> (+75.00%)	:arrow_up:

:mega: Codecov can now indicate which changes are the most critical in Pull Requests. Learn more

[mabdinur]

@Mergifyio backport 1.4

[mergify[bot]]

backport 1.4

✅ Backports have been created

• #4155 chore(telemetry): enable telemetry by default (backport #4003) has been created for branch 1.4