technician in the NYPD's forensics lab has been suspended for allegedly falsifying drug-test results, throwing into question "maybe thousands" of criminal cases -- and prompting a panicked meeting yesterday between cops and the city district attorneys. A Bronx drug trial was even abruptly halted last week because the longtime lab technician, Mariem Megalla, was supposed to testify in that case, sources told The Post. The NYPD last week sent out an emergency e-mail to the city's five DAs warning them about the evidence disaster and telling them to examine pending felony case files for evidence tested by her. In all...