Fix Vale issues for ./administration/postgresql/pgbouncer.md

The following issues occurred when we ran a linting tool called Vale against this topic. To fix the issues, open a merge request for the markdown file, which you'll find in the /doc directory. The first number on each line indicates the line number.

If you feel any of these warnings are incorrect, feel free to create an issue with the tw-test label so we can improve our Vale tests.

| 26:90:gitlab.FutureTense:Avoid using future tense: "We'll also". Use present tense instead. |
| 40:44:gitlab.FutureTense:Avoid using future tense: "will need". Use present tense instead.  |
| 71:70:gitlab.FutureTense:Avoid using future tense: "will cause". Use present tense instead. |