Remove golint test cases for deprecated lints.

I looked for a changelog describing when these lints were deprecated,
but I couldn't find anything. Other lints are still working so /shrug.

prow/plugins/golint/golint_test.go

@@ -345,30 +345,6 @@ func testLintCodeSuggestion(clients localgit.Clients, t *testing.T) {
 			},
 			comment: "",
 		},
-		{
-			name:       "Check variable declaration: should drop type",
-			codeChange: "@@ -0,0 +1,9 @@\n+/*\n+Package bar comment\n+*/\n+package bar\n+\n+func f() {\n+var myInt int = 7\n+}\n+",
-			pullFiles: map[string][]byte{
-				"qux.go": []byte("/*\nPackage bar comment\n*/\npackage bar\n\nfunc f() {\nvar myInt int = 7\n}\n"),
-			},
-			comment: "```suggestion\nvar myInt = 7\n```\nGolint type-inference: should omit type int from declaration of var myInt; it will be inferred from the right-hand side. <!-- golint -->",
-		},
-		{
-			name:       "Check variable declaration: should drop value (int)",
-			codeChange: "@@ -0,0 +1,9 @@\n+/*\n+Package bar comment\n+*/\n+package bar\n+\n+func f() {\n+var myZeroInt int = 0\n+}\n+",
-			pullFiles: map[string][]byte{
-				"qux.go": []byte("/*\nPackage bar comment\n*/\npackage bar\n\nfunc f() {\nvar myZeroInt int = 0\n}\n"),
-			},
-			comment: "```suggestion\nvar myZeroInt int\n```\nGolint zero-value: should drop = 0 from declaration of var myZeroInt; it is the zero value. <!-- golint -->",
-		},
-		{
-			name:       "Check variable declaration: should drop value (float32)",
-			codeChange: "@@ -0,0 +1,9 @@\n+/*\n+Package bar comment\n+*/\n+package bar\n+\n+func f() {\n+var myZeroFlt float32 = 0.\n+}\n+",
-			pullFiles: map[string][]byte{
-				"qux.go": []byte("/*\nPackage bar comment\n*/\npackage bar\n\nfunc f() {\nvar myZeroFlt float32 = 0.\n}\n"),
-			},
-			comment: "```suggestion\nvar myZeroFlt float32\n```\nGolint zero-value: should drop = 0. from declaration of var myZeroFlt; it is the zero value. <!-- golint -->",
-		},
 		{
 			name:       "Check variable declaration: no value suggestion",
 			codeChange: "@@ -0,0 +1,9 @@\n+/*\n+Package bar comment\n+*/\n+package bar\n+\n+func f() {\n+var myZeroRune2 rune\n+}\n+",