JERUSALEM — A series of grisly Palestinian attacks that killed several Israeli civilians has prompted the government to take unprecedented security measures amid growing public debate over whether the specter of another Palestinian Intifada, or uprising, is on the horizon. Israel’s prime minister vowed a “harsh offensive” to counter rising violence that has focused in recent weeks on Jerusalem’s most sensitive holy site sacred to both Muslims and Jews, in a series of so-called “lone wolf” Palestinian attacks against Israelis.