remove deprecated lazy method for option_definition

[ekump]

2.0 Upgrade Guide notes
Configuration options can no longer be defined as lazy. All options are lazily evaluated, making this redundant.

What does this PR do?
Removes a deprecated method on option_definition for defining a configuration option as lazy.

Motivation:

Additional Notes:

How to test the change?

For Datadog employees:

• If this PR touches code that signs or publishes builds or packages, or handles
  credentials of any kind, I've requested a review from @DataDog/security-design-and-guidance.
• This PR doesn't touch any of that.

Unsure? Have a question? Request a review!

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (5cb48c5) 98.13% compared to head (48eeed1) 98.10%.
Report is 107 commits behind head on 2.0.

Additional details and impacted files

@@            Coverage Diff             @@
##              2.0    #3454      +/-   ##
==========================================
- Coverage   98.13%   98.10%   -0.03%     
==========================================
  Files        1249     1261      +12     
  Lines       72086    72985     +899     
  Branches     3372     3419      +47     
==========================================
+ Hits        70741    71605     +864     
- Misses       1345     1380      +35     

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[ivoanjo]

👍 LGTM