Dwayne Montgomery, a former NYPD inspector who has been friends with Mayor Eric Adams for years, pleaded guiltyto conspiracy Monday for his rolein a scheme to funnel illegal donations into the mayor’s 2021 campaign coffers. Montgomery pleaded guilty to one count of conspiracy during a morning hearing in Manhattan Supreme Court, a spokeswoman for District Attorney Alvin Bragg confirmed. Under Montgomery’s plea deal, he was required to admit to conspiring with Shamsuddin Riza and “others” for more than a year to make and facilitate illegal contributions to Mayor Adams’ 2021 City Hall run. Accord…