remove some mimalloc, netsurf and iconv references

Dockerfile

@@ -39,10 +39,6 @@ RUN ZIG=$(grep '\.minimum_zig_version = "' "build.zig.zon" | cut -d'"' -f2) && \
 RUN git submodule init && \
     git submodule update --recursive
 
-RUN make install-libiconv && \
-    make install-netsurf && \
-    make install-mimalloc
-
 # download and install v8
 RUN case $TARGETPLATFORM in \
     "linux/arm64") ARCH="aarch64" ;; \