Simplify regular expression by using raw string literal

Raw string literals use `` ` `` instead of `"` and do not support any escape
sequences. This means that the backslash (`\`) can be used freely,
without the need of escaping.

Since regular expressions have their own escape sequences, raw strings
can improve their readability.

**Before:**

```
regexp.Compile("\\A(\\w+) profile: total \\d+\\n\\z")
```

**After:**

```
regexp.Compile(`\A(\w+) profile: total \d+\n\z`)
```
