fix(api): don't do lld when there is volume in the tip already (#16244)

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# Overview

If you try to do a multi-aspirate or try to do an air-gap after
aspirating it throws an error so just don't do the automatic lld if
there's already liquid in the tip. Still will raise an error if you call
the explicit lld methods.
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api/src/opentrons/protocol_api/instrument_context.py

@@ -266,6 +266,7 @@ def aspirate(
             and well is not None
             and self.liquid_presence_detection
             and self._96_tip_config_valid()
+            and self._core.get_current_volume() == 0
         ):
             self.require_liquid_presence(well=well)