Use reply_callback when using base::GetDelete*Callback() in /chrome/browser/browser_switcher

Currently there's a use pattern as follows:
```
PostTaskAndReply(base::GetDeleteFileCallback(path), callback)
```

This means that when base::GetDeleteFileCallback() returns, the callback
will be called. However, since base::GetDeleteFileCallback() has retry
logic, even after base::GetDeleteFileCallback() returned, there might
still be tasks trying to delete the path. This is not safe if the caller
tries to access the path in the reply callback.

Because of this, a reply callback has been added:
```
base::GetDeleteFileCallback(path, reply_callback)
```
The `reply_callback` is guaranteed be called after the whole retry logic
has been finished.

This CL replaces the pattern
```
PostTaskAndReply(base::GetDeleteFileCallback(path), callback)
```
with
```
PostTask(base::GetDeleteFileCallback(path, callback)),
```
assuming that's the original intention of the code.

This CL was uploaded by git cl split.

R=nicolaso@chromium.org

Bug: 1321695
Change-Id: Ic204aee6694f5afc2bdc1866c482aab7ed98fa32
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3655122
Commit-Queue: Xiaohan Wang <xhwang@chromium.org>
Auto-Submit: Xiaohan Wang <xhwang@chromium.org>
Reviewed-by: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1007427}