feat(tracer): auto-disable tracer when for non-Lambda envs

[michaelbrewer]

Issue #, if available:

• Enable tracing only when running on AWS Lambda #572

Description of changes:

Disables tracer when not running as a lambda ie: LAMBDA_TASK_ROOT env is not set

Changes:

• If LAMBDA_TASK_ROOT is not set then we assume tracer should be disabled
• Remove SAM_LOCAL_ENV and CHALICE_LOCAL_ENV checks
• Update tests

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[michaelbrewer]

@heitorlessa - I am not sure if we need to modify the docs for this. But it should help simplify some people's life.

[codecov-commenter]

Codecov Report

Merging #598 (e65ab8d) into develop (b9a1d54) will decrease coverage by 0.00%.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##           develop     #598      +/-   ##
===========================================
- Coverage    99.95%   99.95%   -0.01%     
===========================================
  Files          113      113              
  Lines         4535     4533       -2     
  Branches       245      245              
===========================================
- Hits          4533     4531       -2     
  Partials         2        2              

Impacted Files	Coverage Δ
aws_lambda_powertools/shared/constants.py	100.00% <100.00%> (ø)
aws_lambda_powertools/tracing/tracer.py	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b9a1d54...e65ab8d. Read the comment docs.