docs: Update SpannerSample.java to align with best practices

[adhiggs]

docs: update SpannerSample.java to align with best practices

Encapsulates both ResultSet statements in try-with-resources statements to align with best practices.

Fixes #3623 ☕️

[adhiggs]

I don't work with github very often, so if I can get a hand in getting the tests passed, I would greatly appreciate it.

[sakthivelmanii]

@adhiggs please update your commit message to follow the convention. https://www.conventionalcommits.org/en/v1.0.0/

[adhiggs]

@adhiggs please update your commit message to follow the convention. https://www.conventionalcommits.org/en/v1.0.0/

@sakthivelmanii - I think I got it? PTAL.

[adhiggs]

@sakthivelmanii - Could you take a look at this request?

[sakthivelmanii]

Please fix the code issue

[sakthivelmanii]

Please fix the checkstyle issues.

Error:  src/main/java/com/example/spanner/SpannerSample.java:[685,7] (indentation) Indentation: 'while' has incorrect indentation level 6, expected level should be 8.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[686,[9](https://github.com/googleapis/java-spanner/actions/runs/15027603684/job/42257173380?pr=3625#step:4:10)] (indentation) Indentation: 'while' child has incorrect indentation level 8, expected level should be 10.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[689,7] (indentation) Indentation: 'while rcurly' has incorrect indentation level 6, expected level should be 8.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[690,5] (indentation) Indentation: 'try rcurly' has incorrect indentation level 4, expected level should be 6.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[691,5] (indentation) Indentation: 'try' has incorrect indentation level 4, expected level should be 6.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[694,7] (indentation) Indentation: 'while' has incorrect indentation level 6, expected level should be 8.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[695,9] (indentation) Indentation: 'while' child has incorrect indentation level 8, expected level should be [10](https://github.com/googleapis/java-spanner/actions/runs/15027603684/job/42257173380?pr=3625#step:4:11).
Error:  src/main/java/com/example/spanner/SpannerSample.java:[698,7] (indentation) Indentation: 'while rcurly' has incorrect indentation level 6, expected level should be 8.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[699,5] (indentation) Indentation: 'try rcurly' has incorrect indentation level 4, expected level should be 6.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[700,3] (indentation) Indentation: 'try rcurly' has incorrect indentation level 2, expected level should be 4.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[701,1] (indentation) Indentation: 'method def rcurly' has incorrect indentation level 0, expected level should be 2.
Error:  src/main/java/com/example/spanner/SpannerSample.java:[702,1] (indentation) CommentsIndentation: Comment has incorrect indentation level 0, expected is 2, indentation should be the same level as line 705.
Error:  Failed to execute goal org.apache.maven.plugins:maven-checkstyle-plugin:3.6.0:check (default-cli) on project spanner-snippets: You have [12](https://github.com/googleapis/java-spanner/actions/runs/15027603684/job/42257173380?pr=3625#step:4:13) Checkstyle violations. -> [Help 1]

https://github.com/googleapis/java-spanner/actions/runs/15027603684/job/42257173380?pr=3625