Updated Dart options to fully include all defaults (#15235)

## DESCRIBE YOUR PR
Made sure Dart options all had defaults where applicable. 

## IS YOUR CHANGE URGENT?  

Help us prioritize incoming PRs by letting us know when the change needs
to go live.
- [ ] Urgent deadline (GA date, etc.): <!-- ENTER DATE HERE -->
- [ ] Other deadline: <!-- ENTER DATE HERE -->
- [x] None: Not urgent, can wait up to 1 week+

## SLA

- Teamwork makes the dream work, so please add a reviewer to your PRs.
- Please give the docs team up to 1 week to review your PR unless you've
added an urgent due date to it.
Thanks in advance for your help!

## PRE-MERGE CHECKLIST

*Make sure you've checked the following before merging your changes:*

- [ ] Checked Vercel preview for correctness, including links
- [ ] PR was reviewed and approved by any necessary SMEs (subject matter
experts)
- [ ] PR was reviewed and approved by a member of the [Sentry docs
team](https://github.com/orgs/getsentry/teams/docs)

Co-authored-by: Shannon Anahata <[email protected]>

Author: sfanahata

docs/platforms/dart/common/configuration/options.mdx

@@ -28,13 +28,13 @@ Turns debug mode on or off. If debug is enabled SDK will attempt to print out us
 
 </SdkOption>
 
-<SdkOption name="diagnosticLevel" type="enum">
+<SdkOption name="diagnosticLevel" type="enum" defaultValue="warning">
 
 Enabling `debug` mode makes the SDK generate as much diagnostic data as possible. However, if you'd prefer to lower the verbosity of the Sentry SDK diagnostics logs, configure this option to set the appropriate level:
 
-- `debug`: **default** The most verbose mode
+- `warning`: **default** Warning that something might not be right
+- `debug`: The most verbose mode
 - `info`: Informational messages
-- `warning`: Warning that something might not be right
 - `error`: Only SDK internal errors are printed
 - `fatal`: Only critical errors are printed
 
@@ -108,7 +108,7 @@ Most SDKs will attempt to auto-discover this value.
 
 </SdkOption>
 
-<SdkOption name="considerInAppFramesByDefault" type="bool">
+<SdkOption name="considerInAppFramesByDefault" type="boolean" defaultValue="true">
 
 Configures whether stack trace frames are considered as in app frames by default.
 You can use this to essentially make `inAppIncludes` or `inAppExcludes` an allow or deny list.
@@ -135,27 +135,27 @@ This option can be overridden using <PlatformIdentifier name="inAppInclude" />.
 
 </SdkOption>
 
-<SdkOption name="sendClientReports" type="bool" availableSince="6.6.0">
+<SdkOption name="sendClientReports" type="boolean" defaultValue="true" availableSince="6.6.0">
 
 Set this boolean to `false` to disable sending of client reports. Client reports are a protocol feature that let clients send status reports about themselves to Sentry. They are currently mainly used to emit outcomes for events that were never sent.
 
 _(New in version 6.6.0)_
 
 </SdkOption>
 
-<SdkOption name="captureFailedRequests" type="bool" availableSince="7.0.0">
+<SdkOption name="captureFailedRequests" type="boolean" defaultValue="true" availableSince="7.0.0">
 
 Once enabled, this feature automatically captures HTTP client errors, like bad response codes, as error events and reports them to Sentry.
 
 _(New in version 7.0.0)_
 
 </SdkOption>
 
-<SdkOption name="maxRequestBodySize" type="enum">
+<SdkOption name="maxRequestBodySize" type="enum" defaultValue="never">
 
 This parameter controls whether integrations should capture HTTP request bodies. It can be set to one of the following values:
 
-- `never`: Request bodies are never sent.
+- `never`: **default** Request bodies are never sent.
 - `small`: Only small request bodies will be captured. The cutoff for small depends on the SDK (typically 4KB).
 - `medium`: Medium and small requests will be captured (typically 10KB).
 - `always`: The SDK will always capture the request body as long as Sentry can make sense of it.