fix: use is None instead of == None in snuba metrics utils

[harshadkhetpal]

Summary

Replaces == None with is None in src/sentry/snuba/metrics/utils.py.

Motivation

PEP 8 specifies that comparisons to None should use identity comparison (is/is not) rather than equality. This is flagged as E711 by flake8/pycodestyle.

Change

# Before
if value == None:
    ...

# After
if value is None:
    ...

Testing

Style/correctness fix only; no behavior change.

[sentry]

Bug: A find-and-replace operation introduced a typo (startisNone) in the docstring for the get_num_intervals() function. This is a documentation-only issue.
_{Severity: LOW}

Suggested Fix

Correct the typo in the docstring on line 491 of src/sentry/snuba/metrics/utils.py. Change If startisNone then it calculates... to If start is None then it calculates... to fix the spacing.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: src/sentry/snuba/metrics/utils.py#L491-L492

Potential issue: In the docstring for the `get_num_intervals()` function, a
find-and-replace operation to convert `== None` to `is None` was applied without
handling spacing correctly. This resulted in the text `If start==None` being changed to
`If startisNone`. This is a cosmetic documentation issue and does not affect the runtime
behavior of the function, as the actual code logic correctly uses `if start is None:`.

_{Did we get this right? 👍 / 👎 to inform future reviews.}