Fix the ExtendedClassInfo for trace elements deobfuscated by the preceding rewriter.

[jpenilla]

Another solution would be to reorder the rewrites and make the StacktraceDeobfuscator handle extended traces. This is arguably not that important of a fix as only server classes should be getting deobfed, so we can easily deduce that the ?:? with a net.minecraft/com.mojang package means it's a deobfed server class.