Update all Account records to standardize their Rating field based on AnnualRevenue thresholds. Return the number of accounts successfully updated.

Apply the following rating rules:

• AnnualRevenue >= 100,000,000 -> Rating = 'Hot'
• AnnualRevenue >= 10,000,000 and < 100,000,000 -> Rating = 'Warm'
• AnnualRevenue < 10,000,000 (or null) -> Rating = 'Cold'

Use Database.update with allOrNone=false to handle partial failures gracefully.

Returns:

• Integer: The number of accounts successfully updated

Requirements:

• Query all Account records with Id, AnnualRevenue, and Rating fields
• Apply rating logic based on revenue thresholds
• Use Database.update() with allOrNone=false
• Count successful results from SaveResult array

Example:

Integer updated = standardizeRatings();
// Account with $150M revenue gets Rating = 'Hot'
// Account with $25M revenue gets Rating = 'Warm'
// Account with $5M revenue gets Rating = 'Cold'
// Returns: Total number of accounts successfully updated