tpl/partials: Make sure a cached partial is invoked only once

This commit revises the locking strategy for `partialCached`. We have added a benchmark that may be a little artificial, but it should at least show that we're not losing any performance over this:

```bash
name              old time/op    new time/op    delta
IncludeCached-10    12.2ms ± 2%    11.3ms ± 1%   -7.36%  (p=0.029 n=4+4)

name              old alloc/op   new alloc/op   delta
IncludeCached-10    7.17MB ± 0%    5.09MB ± 0%  -29.00%  (p=0.029 n=4+4)

name              old allocs/op  new allocs/op  delta
IncludeCached-10      128k ± 1%       70k ± 0%  -45.42%  (p=0.029 n=4+4)
```

This commit also revises the template metrics hints logic a little, and add a test for it, which output is currently this:

```bash
 cumulative       average       maximum      cache  percent  cached  total
       duration      duration      duration  potential   cached   count  count  template
     ----------      --------      --------  ---------  -------  ------  -----  --------
      163.334µs     163.334µs     163.334µs          0        0       0      1  index.html
       23.749µs       5.937µs      19.916µs         25       50       2      4  partials/dynamic1.html
        9.625µs       4.812µs        6.75µs        100       50       1      2  partials/static1.html
        7.625µs       7.625µs       7.625µs        100        0       0      1  partials/static2.html
```

Some notes:

* The duration now includes the cached invocations (which should be very short)
* A cached template gets executed once before it gets cached, so the "percent cached" will never be 100.

Fixes #4086
Fixes #9506

1 files changed, 4 insertions, 3 deletions

diff --git a/htesting/hqt/checkers.go b/htesting/hqt/checkers.go
index c12f78034..e518dfa1f 100644
--- a/htesting/hqt/checkers.go
+++ b/htesting/hqt/checkers.go
@@ -63,7 +63,7 @@ type stringChecker struct {
 	argNames
 }
 
-// Check implements Checker.Check by checking that got and args[0] represents the same normalized text (whitespace etc. trimmed).
+// Check implements Checker.Check by checking that got and args[0] represents the same normalized text (whitespace etc. removed).
 func (c *stringChecker) Check(got interface{}, args []interface{}, note func(key string, value interface{})) (err error) {
 	s1, s2 := cast.ToString(got), cast.ToString(args[0])
 
@@ -81,11 +81,12 @@ func (c *stringChecker) Check(got interface{}, args []interface{}, note func(key
 }
 
 func normalizeString(s string) string {
+	s = strings.ReplaceAll(s, "\r\n", "\n")
+
 	lines := strings.Split(strings.TrimSpace(s), "\n")
 	for i, line := range lines {
-		lines[i] = strings.TrimSpace(line)
+		lines[i] = strings.Join(strings.Fields(strings.TrimSpace(line)), "")
 	}
-
 	return strings.Join(lines, "\n")
 }