Designate H1:PEM-EX_VMON_ETMX_ESDPOWERMINUS18_DQ as unsafe after safety study

No notable change in safety was observed at LLO. At LHO, H1:PEM-EX_VMON_ETMX_ESDPOWERMINUS18_DQ was found to be unsafe by pointy, though it was not obvious in omegascans. We decided to designate it as unsafe, since H1:PEM-EX_VMON_ETMX_ESDPOWER18_DQ and other ESDPOWER channels were designated as unsafe in the last set (ER15) of safety studies, so it is plausible that the ESDPOWERMINUS18 channel is also unsafe.

Described in https://dcc.ligo.org/T2300246.