Fix numeric_state condition spamming on unavailable state

[OttoWinter]

Description:

When a sensor reports an unknown or unavailable state, numeric_state conditions based off of this sensor will spam the logs:

Note this doesn't change actually any behavior, it simply doesn't spam the log on these two specific values.

Example entry for configuration.yaml (if applicable):

condition: numeric_state
entity_id: sensor.temperature
below: 42

Checklist:

• The code change is tested and works locally.

If the code does not interact with devices:

• Local tests with tox run successfully. Your PR cannot be merged unless tests pass
• Tests have been added to verify that the new code works.