Replace Linkup web search with Serper (#717) #778

Job	Run time
build-freebuff	1m 13s
build-and-smoke-freebuff-windows	2m 14s
e2e-slash-commands	1m 10s
e2e-agent-startup	2m 21s
e2e-help-command	1m 9s
e2e-version	53s
e2e-code-edit	51s
e2e-startup	1m 17s
e2e-ads-behavior	1m 10s
e2e-terminal-command	1m 2s
	13m 20s

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