internal/scan: remove informational header for package and module mode

It might be confusing and is really not adding any value to the output.

Change-Id: Icb65714f5dd111aa875bd88c4e5925a2cab74a19
Reviewed-on: https://go-review.googlesource.com/c/vuln/+/551378
Run-TryBot: Zvonimir Pavlinovic <zpavlinovic@google.com>
Reviewed-by: Maceo Thompson <maceothompson@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>

cmd/govulncheck/testdata/testfiles/source-module/source_module_text.ct

@@ -4,8 +4,6 @@
 $ govulncheck -scan module -C ${moddir}/multientry
 Scanning your code across 2 dependent modules for known vulnerabilities...
 
-=== Informational ===
-
 There are 2 vulnerabilities in modules that you require. Use
 -scan=symbol with govulncheck for more fine grained vulnerability
 detection.

cmd/govulncheck/testdata/testfiles/source-package/source_package_text.ct

@@ -3,8 +3,6 @@
 $ govulncheck -scan package -C ${moddir}/multientry .
 Scanning your code and P packages across M dependent modules for known vulnerabilities...
 
-=== Informational ===
-
 Found 1 vulnerability in packages that you import. There is also 1
 vulnerability in modules that you require. Use -scan=symbol with
 govulncheck for more fine grained vulnerability detection.

internal/scan/testdata/module-vuln.txt

@@ -1,5 +1,3 @@
-=== Informational ===
-
 There is 1 vulnerability in modules that you require. Use -scan=symbol
 with govulncheck for more fine grained vulnerability detection.
 See https://pkg.go.dev/golang.org/x/vuln/cmd/govulncheck for details.

internal/scan/testdata/multi-stack-modlevel.txt

@@ -1,5 +1,3 @@
-=== Informational ===
-
 There are 2 vulnerabilities in modules that you require. Use
 -scan=symbol with govulncheck for more fine grained vulnerability
 detection.

internal/scan/testdata/package-vuln.txt

@@ -1,5 +1,3 @@
-=== Informational ===
-
 Found 1 vulnerability in packages that you import. Use -scan=symbol
 with govulncheck for more fine grained vulnerability detection.
 See https://pkg.go.dev/golang.org/x/vuln/cmd/govulncheck for details.

internal/scan/text.go

@@ -154,7 +154,9 @@ func (h *TextHandler) byVulnerability(findings []*findingSummary) {
 	if onlyImported+onlyRequired == 0 {
 		return
 	}
-	h.style(sectionStyle, "=== Informational ===\n\n")
+	if h.scanLevel.WantSymbols() {
+		h.style(sectionStyle, "=== Informational ===\n\n")
+	}
 	var informational strings.Builder
 	if onlyImported > 0 {
 		informational.WriteString("Found " + fmt.Sprint(onlyImported))