Use STARTS_WITH, since it's more specific

Co-Authored-By: Guillaume Gomez <guillaume1.gomez@gmail.com>

Author: notriddle

src/test/rustdoc-gui/search-tab-change-title-fn-sig.goml

@@ -5,28 +5,28 @@ write: (".search-input", "Foo")
 // Waiting for the search results to appear...
 wait-for: "#titles"
 assert-attribute: ("#titles > button:nth-of-type(1)", {"class": "selected"})
-assert-text: ("#titles > button:nth-of-type(1)", "In Names", CONTAINS)
+assert-text: ("#titles > button:nth-of-type(1)", "In Names", STARTS_WITH)
 
 // Now try search-by-return
 goto: file://|DOC_PATH|/test_docs/index.html
 write: (".search-input", "-> String")
 // Waiting for the search results to appear...
 wait-for: "#titles"
 assert-attribute: ("#titles > button:nth-of-type(1)", {"class": "selected"})
-assert-text: ("#titles > button:nth-of-type(1)", "In Function Signature", CONTAINS)
+assert-text: ("#titles > button:nth-of-type(1)", "In Function Signature", STARTS_WITH)
 
 // Try with a search-by-return with no results
 goto: file://|DOC_PATH|/test_docs/index.html
 write: (".search-input", "-> Something")
 // Waiting for the search results to appear...
 wait-for: "#titles"
 assert-attribute: ("#titles > button:nth-of-type(1)", {"class": "selected"})
-assert-text: ("#titles > button:nth-of-type(1)", "In Function Signature", CONTAINS)
+assert-text: ("#titles > button:nth-of-type(1)", "In Function Signature", STARTS_WITH)
 
 // Try with a search-by-return with no results
 goto: file://|DOC_PATH|/test_docs/index.html
 write: (".search-input", "usize pattern")
 // Waiting for the search results to appear...
 wait-for: "#titles"
 assert-attribute: ("#titles > button:nth-of-type(1)", {"class": "selected"})
-assert-text: ("#titles > button:nth-of-type(1)", "In Function Signature", CONTAINS)
+assert-text: ("#titles > button:nth-of-type(1)", "In Function Signature", STARTS_WITH)