clear `cachedSearchTerm` when decorations are cleared (#3750)
clear `cachedSearchTerm` when decorations are cleared (#3750)


Tyriar/xterm.js,Tyriar/xterm.js,Tyriar/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,xtermjs/xterm.js,Tyriar/xterm.js,xtermjs/xterm.js,Tyriar/xterm.js,xtermjs/xterm.js