fix(pdb): remove default maxUnavailable/minAvailable values (#839)

**Description**
Currently, both `maxUnavailable` and `minAvailable` are set to `1` in
common.yaml. This results in bolt values being set if
`PodDisruptionBudget` is enabled in any Helm charts. Having both fields
set results in Argo failing to sync, because they are
mutually-exclusive.

The docs already note that one of these fields must be set:
https://truecharts.org/common/poddisruptionbudget/#name, so I do not
think they should both be set by default, since it is more prone to
error.

⚒️ Fixes  # <!--(issue)-->

**⚙️ Type of change**

- [ ] ⚙️ Feature/App addition
- [x] 🪛 Bugfix
- [ ] ⚠️ Breaking change (fix or feature that would cause existing
functionality to not work as expected)
- [ ] 🔃 Refactor of current code

**🧪 How Has This Been Tested?**

**📃 Notes:**

**✔️ Checklist:**

- [x] ⚖️ My code follows the style guidelines of this project
- [x] 👀 I have performed a self-review of my own code
- [x] #️⃣ I have commented my code, particularly in hard-to-understand
areas
- [x] 📄 I have made corresponding changes to the documentation
- [x] ⚠️ My changes generate no new warnings
- [x] 🧪 I have added tests to this description that prove my fix is
effective or that my feature works
- [x] ⬆️ I increased versions for any altered app according to semantic
versioning
- [x] I made sure the title starts with `feat(chart-name):`,
`fix(chart-name):` or `chore(chart-name):`

**➕ App addition**

If this PR is an app addition please make sure you have done the
following.

- [ ] 🖼️ I have added an icon in the Chart's root directory called
`icon.png`

---

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library/common/values.yaml

@@ -728,9 +728,9 @@ podDisruptionBudget:
     # -- Custom Selector Labels
     # customLabels:
     #   customKey: customValue
+    # maxUnavailable: 1
+    # minAvailable: 1
     targetSelector: main
-    minAvailable: 1
-    maxUnavailable: 1
 
 webhook:
   validating: