Fix unused import left in #31564

[eerii]

#31564 had an unused import issue while compiling. I changed std::mem::take to mem::take to use the import and be consistent with the rest of std uses. (Sorry for not noticing before the merge!)

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• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• These changes fix unused import: mem, in components/net/image_cache.rs #31607
• These changes do not require tests because they are just a fix for an import warning

[Loirooriol]

Thanks!